Monthly report documenting contracts for road construction and maintentance in Texas, organized by county and district. It includes information about each project including contractor, dates, costs, and other relevant data.

Despite the fact that chemical weathering of silicate rocks plays an important role in the draw-down of CO{sub 2} over geologic time scales (Berner and Berner, 1996), the overall controls on the rate of chemical weathering are still not completely understood. Lacking a mechanistic understanding of these controls, it remains difficult to evaluate a hypothesis such as that presented by Raymo and Ruddiman (1992), who suggested that enhanced weathering and CO{sub 2} draw-down resulting from the uplift of the Himalayas contributed to global cooling during the Cenozoic. At an even more fundamental level, the three to four order of magnitude discrepancy between laboratory and field weathering rates is still unresolved (White et al., 1996). There is as yet no comprehensive, mechanistic model for silicate chemical weathering that considers the coupled effects of precipitation, vadose zone flow, and chemical reactions. The absence of robust process models for silicate weathering and the failure to resolve some of these important questions may in fact be related-the controls on the overall rates of weathering cannot be understood without considering the weathering environment as one in which multiple, time-dependent chemical and physical processes are coupled (Malmstrom, 2000). Once chemical weathering is understood at a mechanistic …

We present experimental results in three areas. Solar cells with an efficiency of 19% have been fabricated with an absorber bandgap in the range of 1.1-1.2 eV. Properties of solar cells fabricated with and without an undoped ZnO layer were compared. The data show that high efficiency cells can be fabricated without using the high-resistivity or undoped ZnO layer. Properties of CIGS solar cells were fabricated from thin absorbers (1 {micro}m) deposited by the three-stage process and simultaneous co-deposition of all the elements. In both cases, solar cells with efficiencies of 16%-17% are obtained.

We report the deposition of improved hydrogenated amorphous silicon germanium (a-SiGe:H) films by the hot wire CVD (HWCVD) technique using a tantalum filament operating at a low temperature. We gauge the material quality of the a-SiGe:H films by comparing infrared, small angle X-ray scattering (SAXS), photocapacitance, and conductivity measurements to earlier results, and fabricate single-junction n-i-p solar cell devices using these i-layers.

By analogy to the different accretion states observed in black-hole X-ray binaries (BHXBs), it appears plausible that accretion disks in active galactic nuclei (AGN) undergo a state transition between a radiatively efficient and inefficient accretion flow. If the radiative efficiency changes at some critical accretion rate, there will be a change in the distribution of black hole masses and bolometric luminosities at the corresponding transition luminosity. To test this prediction, the author considers the joint distribution of AGN black hole masses and bolometric luminosities for a sample taken from the literature. The small number of objects with low Eddington-scaled accretion rates m < 0.01 and black hole masses M{sub BH} < 10{sup 9} M{sub {circle_dot}} constitutes tentative evidence for the existence of such a transition in AGN. Selection effects, in particular those associated with flux-limited samples, systematically exclude objects in particular regions of the (M{sub BH}, L{sub bol}) plane. Therefore, they require particular attention in the analysis of distributions of black hole mass, bolometric luminosity, and derived quantities like the accretion rate. The author suggests further observational tests of the BHXB-AGN unification scheme which are based on the jet domination of the energy output of BHXBs in the hard state, …

With the publication of IEEE 1547-2003(TM) Standard for Interconnecting Distributed Resources With Electric Power Systems, the electric power industry has a need to develop tests and procedures to verify that interconnection equipment meets 1547 technical requirements. A new standard, IEEE P1547.1(TM), is being written to give detailed tests and procedures for confirming that equipment meets the interconnection requirements. The National Renewable Energy Laboratory has been validating test procedures being developed as part of IEEE P1547.1. As work progresses on the validation of those procedures, information and test reports are passed on to the working group of IEEE P1547.1 for future revisions.

A preliminary measurement of the t{bar t} production cross section at {radical}s = 1.96 TeV is presented. The {mu}-plus-jets final state is analyzed in a data sample of 94 pb{sup -1} and a total of 14 events are selected with a background expectation of 11.7 {+-} 1.9 events. The measurement yields: {sigma}{sub p{bar p} {yields} t{bar t} + X} = 2.4{sub -3.5}{sup +4.2}(stat.){sub -2.6}{sup +2.5}(syst.) {+-} 0.3(lumi.) pb. The analysis, being part of a larger effort to re-observe the top quark in Tevatron Run II data and to measure the production cross section, is combined with results from all available analyses channels. The combined result yields: {sigma}{sub p{bar p}} {yields} t{bar t} + X = 8.1{sub -2.0}{sup +2.2}(stat.){sub -1.4}{sup +1.6}(syst.) {+-} 0.8(lumi.) pb.

This report is a summary of the discussion sessions of the 12th Workshop on Crystalline Silicon Solar Cells and Processes. The theme of the workshop was"Fundamental R&D in c-Si: Enabling Progress in Solar-Electric Technology." This theme was chosen to reflect a concern that the current expansion in the PV energy production may redirect basic research efforts to production-oriented issues. The PV industry is installing added production capacity and new production lines that include the latest technologies. Once the technologies are selected, it is difficult to make changes. Consequently, a large expansion can stagnate the technologies and diminish interest in fundamental research. To prevent the fundamental R&D program from being overwhelmed by the desire to address immediate engineering issues, there is a need to establish topics of fundamental nature that can be pursued by the universities and the research institutions. Hence, one of the objectives of the workshop was to identify such areas for fundamental research.

The Red-Sequence Cluster Survey (RCS) provides a large and deep photometric catalog of galaxies in the z' and R{sub c} bands for 90 square degrees of sky, and supplemental V and B data have been obtained for 33.6 deg{sup 2}. They compile a photometric redshift catalog from these 4-band data by utilizing the empirical quadratic polynomial photometric redshift fitting technique in combination with CNOC2 and GOODS/HDF-N redshift data. The training set includes 4924 spectral redshifts. The resulting catalog contains more than one million galaxies with photometric redshifts < 1.5 and R{sub c} < 24, giving an rms scatter {delta}({Delta}z) < 0.06 within the redshift range 0.2 < z < 0.5 and {sigma}({Delta}z) < 0.11 for galaxies at 0.0 < z < 1.5. They describe the empirical quadratic polynomial photometric redshift fitting technique which they use to determine the relation between red-shift and photometry. A kd-tree algorithm is used to divide up the sample to improve the accuracy of the catalog. They also present a method for estimating the photometric redshift error for individual galaxies. They show that the redshift distribution of the sample is in excellent agreement with smaller and much deeper photometric and spectroscopic redshift surveys.

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In this report we present the research plan for the RHIC spin program. The report covers (1) the science of the RHIC spin program in a world-wide context; (2) the collider performance requirements for the RHIC spin program; (3) the detector upgrades required, including timelines; (4) time evolution of the spin program.

The primary value of the Pacific Northwest National Laboratory (PNNL) Voluntary Protection Program (VPP) is the ongoing partnership between management and staff committed to change Laboratory safety culture one step at a time. VPP enables PNNL's safety and health program to transcend a top-down, by-the-book approach to safety, and it also raises grassroots safety consciousness by promoting a commitment to safety and health 24 hours a day, 7 days a week. PNNL VPP is a dynamic, evolving program that fosters innovative approaches to continuous improvement in safety and health performance at the Laboratory.

This paper presents a personal account of the scientific and professional adventures of Bikash Sinha on the occasion of the celebration of his 60th birthday held in Calcutta on Feb 7, 2005.

Photoelectron spectroscopy was used to determine the compositional and electronic changes occurring in Cu(In,Ga)Se2 thin films as a result of immersion in aqueous ammonia solution. We find that NH4OH-treated CIGS surfaces are preferentially etched of indium and gallium, resulting in the formation of a thin layer of a degenerate Cu-Se compound that we tentatively identify as Cu2Se. The work function of ammonia-treated samples is found to increase by 0.6 eV relative to as-grown CIGS thin films. The uniformity of chemical bath effects (etching & deposition) was found to be improved by the addition to the bath of a non-ionic surfactant. Initial device results show that the new surfactant-based chemical bath deposition (CBD) method may lead to better and thinner CdS buffer layers.

This fact sheets provides a summary of geothermal potential, issues, and current development in Oregon. This fact sheet was developed as part of DOE's GeoPowering the West initiative, part of the Geothermal Technologies Program.

GaInNAs, potentially useful in a 4-junction GaInP2/GaAs/GaInNAs/Ge solar cell, suffers from very low minority-carrier collection lengths. To date, the currents available from GaInNAs solar cells are not high enough to increase the efficiency of a 3-junction device by adding this fourth junction. Here, we grow p-i-n GaInNAs solar cells by molecular-beam epitaxy with wide, intrinsic base layers and internal quantum efficiencies near 1.0. If similar 1.0-eV GaInNAs junctions can be successfully integrated into the 3-junction structure, the resulting 4-junction cell would have a higher efficiency.

With the assistance of NREL's PV Manufacturing R&D program, ITN Energy Systems, Inc. and Global Solar Energy, Inc. continued the advancement of CIGS production technology by developing trajectory-oriented predictive/control models, fault-tolerance control, control-platform development, in-situ sensors, and process improvements. Modeling activities to date include developing physics-based and empirical models for CIGS and physics-based Mo deposition processing, implementing model-based control for CIGS processing, and applying predictive models to the construction of new evaporation sources. Model-based control is enabled by implementing reduced or empirical models into a control platform. Reliability improvement activities include systematic development of fault-prevention procedures (e.g., preventative maintenance schedules) and detection/reconfiguration of sensor and other hardware failures for the full range of CIGS PV production deposition processes. In-situ sensor development activities have resulted in improved control and indicate the potential for enhanced process status monitoring and control of all deposition processes. In spite of the short time since the program was initiated, substantial process improvements have been made, including significant improvement in CIGS uniformity, thickness control (e.g., 71% reduction in Cu variability), yield, and throughput.

This report summarizes the results of a lifecycle assessment of a renewable hydrogen production process employing wind/electrolysis. Resource consumption, energy requirements, and emissions were determined in a cradle-to-grave manner on the operations required to transform raw materials into useful products, including the material production processes required to construct the wind turbines, electrolyzer, and hydrogen storage tanks.

Measurement of recombination and minority-carrier lifetimes has become a central activity in photovoltaic technology. The primary measurement techniques for silicon technologies are based on photoconductive decay (PCD) and microwave reflectance (mPCD). The measurement of the correct recombination lifetime depends on the carriers being confined to a given spatial region of a diagnostic structure. The internal electric fields separate the charges, and the measured value does not represent the real minority-carrier lifetime. In these cases, the measured quantity is a function of the true lifetime and the sample structure. Here, we examine these effects, both experimentally and theoretically, for the n+-p device structure common to terrestrial photovoltaics.

We report on a direct measurement of two-dimensional potential distribution on the surface of Cu(In,Ga)Se2 thin films using a nanoscale electrical characterization of scanning Kelvin probe microscopy both in air and in ultra-high vacuum. The potential measurement reveals a higher surface potential or a smaller work function on grain boundaries (GBs) of the film than on the grain surfaces. This demonstrates the existence of a local built-in potential on GBs, and the GB is positively charged. The role of the built-in potential in device performance was further examined and found to be positive, by tuning Ga content or bandgap of the film. With increasing Ga content, the potential drops sharply in a Ga range of 28%-38%. Comparing the change in the built-in potential to the theoretical and experimental photoconversion efficiencies, we conclude that the potential plays a significant role in the device conversion efficiency of NREL's three-stage Cu(In,Ga)Se2 device.

Nevada has a vast potential for electricity generation using solar power. An examination of the stock of renewable resources in Nevada proves that the state has the potential to be a leader in renewable-electric generation--one of the best in the world. This study provides estimates on the economic impact in terms of employment, personal income, and gross state product (GSP) of developing a portion of Nevada's solar energy generation resources.

This report describes the feasibility, calibration, and safety considerations of a non-destructive, in situ, quantitative, volumetric soil carbon analytical method based on inelastic neutron scattering (INS). The method can quantify values as low as 0.018 gC/cc, or about 1.2% carbon by weight with high precision under the instrument's configuration and operating conditions reported here. INS is safe and easy to use, residual soil activation declines to background values in under an hour, and no radiological requirements are needed for transporting the instrument. The labor required to obtain soil-carbon data is about 10-fold less than with other methods, and the instrument offers a nearly instantaneous rate of output of carbon-content values. Furthermore, it has the potential to quantify other elements, particularly nitrogen. New instrumentation was developed in response to a research solicitation from the U.S. Department of Energy (DOE LAB 00-09 Carbon Sequestration Research Program) supporting the Terrestrial Carbon Processes (TCP) program of the Office of Science, Biological and Environmental Research (BER). The solicitation called for developing and demonstrating novel techniques for quantitatively measuring changes in soil carbon. The report includes raw data and analyses of a set of proof-of-concept, double-blind studies to evaluate the INS approach in the first phase …

Fact sheet describes the alternative fuel successes realized by two Minnesota state fleets.

The approach in this subcontract was to use unique analytical tools available at Berkeley to perform systematic fundamental physical studies of the distribution and chemical state of metal clusters in a variety of multicrystalline silicon materials. Two analytical techniques were essential for the success of this project. The total metal concentration in the areas of multicrystalline silicon with high and low lifetime was determined by neutron activation analysis, a technique that involves irradiation of a sample with neutrons in a nuclear reactor and analysis of its residual radioactivity. The distribution and chemical state of metal clusters was characterized by synchrotron radiation-based X-ray microscopes available at the Advanced Light Source (Beamlines 10.3.1 and 10.3.2) at Lawrence Berkeley National Laboratory and Advanced Photon Source (Beamlines 2-ID-D and 20-ID-B) at Argonne National Laboratory.